A conventional bubble level may be used for checking horizontality or verticality. The bubble level includes a sealed glass container containing water and a small air bubble existing therein. For obtaining the measurement result, a great error may be caused by the observer""s visual reading on the bubble position because of the following factors:
1. The deviation or difference of angle of view when observing the bubble position in the level may be caused from time to time by same or different observers;
2. The readings of the measurement results may also be different as effected by the variation of incoming light directions or angles or the different light intensity in the measurement environment.
3. It is lacking of additional systematic equipments provided for optically or electronically sensing or recording the measurement result.
The present inventor has found the drawbacks of conventional bubble level and invented the present bubble leveling means for reliably sensing the measurement result.
The object of the present invention is to provide a bubble leveling device including a bubble level having a gas bubble formed on a liquid surface, an illuminator projecting light through or towards the gas bubble for producing an optical image of the gas bubble, and a sensor having a coordinate screen for locating the optical image of the gas bubble on the screen for checking the coincidence or deviation of the image with or from the coordinate center of the screen for reliably checking the horizontality or inclination angle as measured by the bubble leveling device.